Thunder Pirate King
by OP MC
Summary: Rayden, an elite bounty hunter from earth is reborn into this turbulent world of one piece after being betrayed by his companions. His rise to the top will bring turbulence and chaos to every ocean he sails through! Ruthlessness is his synonym. From beginning to end, he has one purpose; any person that crosses his bottom line, even if it is the whole world, shall be destroyed!
1. Chapter 1 - Rayden D Chronus (Part 1)

**Chapter 1: Rayden D. Chronus (Part 1)**

East Blue, Yotsuba Island Region!

Shakka Town.

In the middle of the street, Captain Rand, who was carrying a giant axe on his shoulder, looked at the dead bodies that were scattered around him with a deadpan expression. Together with his crew, they had looted this small town and anyone who dared to stand up against them had been mercilessly killed.

Even though they had successfully stifled any opposition that might come from this town, they had also suffered some casualties. His originally 12 crew members were now only left with five. But the haul they had looted from this town made him very satisfied. Looking at the giant chest filled with treasures that was placed in front of him, he turned around and asked the few pirates he had left, "Are these all the treasures?"

"Yes, Captain, that's all the treasures we found!" the pirate closest to him answered.

"Good! Prepare to evacuate this village immediately before the Navy Arrives!" he said to his remaining crew immediately with satisfaction as he moved towards the exit of this town.

What was now his first priority was to leave this town immediately before the Navy from Shells Town which is very close to his place arrives. However, before he could move a few more steps, he noticed a young man wearing a white open-front shirt and black boots, black trousers with an eyelet-studded orange belt with a leather hat on his head leaning with his arms crossed against a house across from him. This young man had two blades hanged on both sides of his waist whilst holding a modified flintlock in his right hand and a paper in his left.

He didn't know how long this young man had been here but from his manner, it seemed he had been standing there staring at him for quite a while.

"Hmm? Who is this little devil?" Frowning, Rand asked his subordinate beside him. After looting this town and killing a few of its inhabitants, the remaining citizens had been so scared of them that they had shut themselves in their rooms. So he was quite surprised to see this young man with a weapon appearing in front of him as if he wasn't afraid of him at all.

When the remaining pirates heard Captain Rand's question, they also turned and saw this young man. This young man had appeared out of nowhere and was just standing there starring at them. Was he planning to stop them?

Waking up from their surprise, most of them began to laugh! How can such a small devil stop them? Some of them shook their wrists and took out their guns and aimed directly at the youth at the end of the street.

"Hey! Kid, do you want to die? Leave here at once before we send you to meet your maker!" Some of them began to shout!

Despite facing all these weapons pointing at him and urging him to leave, this young man was in no hurry to leave. Instead he looked directly at Captain Rand and smiled, "A reward of ฿ 4,000,000, 'Bloody Axe' Rand, is it?"

"Kid, stop spouting crap! Leave here before I get angry!" even though he displaying an angry and impatient manner, this wasn't how he felt at all.

At this time, Rand's chin was slightly lifted up, revealing a hint of arrogance. In East blue which was considered the weakest ocean, the average bounty of pirates is ฿ 3,000,000. Any higher means that, that pirate is an elite among the weak. As a pirate, he hoped he had a high reward, and the reward of ฿ 4,000,000 was not low, which was why he had always felt very good and proud about himself.

"Oh, it seems I didn't identify the wrong person!" seeing that Captain Rand didn't deny what he just said, the young man nodded and gently dropped the paper in his hand and said, "Then, I'll accept the head of a ฿ 4,000,000 pirate!"

'Boom! Boom! Boom!'

Almost at the moment when his voice fell, the young man raised his modified flintlock in a swift speed, and shot six consecutive times at Rand and five of his subordinates. The six shots were so fast and steady that it seemed as if he was an experienced gunner who had done this for a long time.

The pirates apparently did not expect that the young people facing them would be courageous enough to fire at them so they didn't have time to dodge.

'Bang! Bang…Bang!' Six shots, five fell to the ground!

The only shot that didn't achieve its intended effect was the one he fired at Captain Rand who was fast and alert enough to block that gun shot with the huge axe on his shoulder.

At this time, the paper that was thrown aside by the young man slowly finally landed on the floor. It was a bounty poster. The wanted figure on it was the same as the man in front of him, 'Bloody Axe' Rand!

Even though Captain Rand had blocked the young man's bullet, he couldn't stop the death of the rest of his men. He watched as his five men were knocked down, and he began to fume with rage. Even though he was a very cold hearted man and killed without batting an eye, he still felt pain when he saw his subordinates that he had tried very hard to gather die in front of him.

"You! ... Damn it!" He roared, raised his heavy axe with both hands, and rushed up to the young man, slamming his weapon at him. The anger he felt at this time fueled the swing of his axe. The momentum that he unleashed gave the impression that this young man would be chopped in two the moment his weapon made contact.

However, in the face of the rushing Rand, the young man did not panic. He hurriedly tossed aside his flintlock ad unsheathed his two blade swinging it to clash with Rand. When Rand saw this, he laughed inwardly because among his peers, he was known for his monstrous strength. His axe was not only huge, but the materials were very special. It was both hard and extremely heavy! He thought this young man was very stupid for trying to clash head on against him.

"Death!" Captain Rand shouted!

'Bang!'

But the moment when the young man's blades clashed with the Axe, Rand's facial expression suddenly changed. He felt the abnormal power that was transmitted through his axe which made his hands shake.

'Bang! Bang! Bang!' He was repelled and moved three steps backwards. Every step he took left a deep impression on the ground.

"What!" Rand just couldn't believe that such thin looking hands could unleash such strength. The young man also shook his hands to release the numbness that he also felt in his hands. He looked at his axe only to realise that there was a gap in it.

"That's what you would expect from a ฿ 4,000,000 bounty pirate!" the young man said while preparing himself, "you've had your chance, now it my turn!"

Without even waiting for Captain Rand to reorient himself, the young man raised his blades and rushed at him.


	2. Chapter 2 - Rayden D Chronus (Part 2)

**Chapter 2: Rayden D. Chronus (Part 2)**

The two fighters clashed once again!

'Bang! Bang! Bang…Bang!' Eight consecutive strikes! Four from his left and four from his right. This was a unique blade skill which borrowed the recoil of the first strike to increase the strength for the next strike. Because of this, from the second strike, the strength of his swings increases gradually until in peaks at 2.5x its normal strength on the last strike. because he was ambidextrous, he could execute this skill with both hands simultaneously.

'Bang!" with each strike, Rand felt his hands shake and the feeling disappear from his hands until he was finally blown away on the last strike and slammed against the house behind him.

'Boom!'

The force of this last strike was so strong that when Rand slammed against the walls of the brick house, it caused the whole house to collapse onto him.

"This Rand is very good! He was able to take all eight strikes!" the young man said as he waited for Captain Rand to come out of the rubble.

"Hmm?" However he suddenly felt a special energy enter him. The feeling it brought was very refreshing. This was a sign which told him that the last strike must have killed the 'Bloody Axe' Rand!

With a thought, a light blue transparent holographic projection appeared in front of him.

* * *

 **Name** : Rayden D. Chronos

 **Age** : 15

 **Basic Attributes**

 **Strength** : 2.6, **Agility:** 2.4, **Vitality:** 2.3, **Intelligence:** 3.6, **Awareness:** 3.9

 **Talent Ability** : Lightning Core ( **Locked** ) - [ _Minimum Requirements for Unlocking: Strength 2.5, Agility 2.5, Vitality 2.5, and Intelligence 3.0_ ]

 **Battle Energy** : 30

 **Battle Skills**

 **Thunder Force Blade Art** : 10/500

 **Marksmanship** : 22/30

 **Close Combat Skill** : 41/60

 **Comprehensive Combat Assessment** : F+

* * *

"At least with these Battle Energy, I can finally increase my agility and vitality attributes to the standard to activate the Lightning core!" the young man sighed in relief when he saw that his Battle energy had increased by 20 points. So he now had thirty points.

This young man's name is Rayden Cronus and he is not an original inhabitant of this world. He was reborn two years ago in the body of the then twelve year old youth who had died after his village had been attacked by pirates.

In his previous life, Rayden was one of the highest ranked bounty hunters in the Underworld on earth. Ever since his debut eight years ago together with his four companions, there was no country they could not infiltrate and no assignment they couldn't complete. They took only eight years to rise from an obscure mercenary group into one of the best ranked mercenary groups on earth.

At the same time, the name "Ghost Blade" who was also rumored to be the leader of this group sent a sensation throughout the dark world. In terms of marksmanship, he was simply unparalleled. He could snipe targets who were 3500 meters away from him which a lot of obstruction in between them. But what made him even more famous was his close combat skills as well as his blade skills. In a scientifically developed world where most of the top warriors and mercenaries used powerful fire arms, it was surprising that a mercenary that used only a thin steel blade got to such a level. His speed and blade technique was so fast that virtually no one could keep up with him.

No one knew how a normal person could push his body to such extreme lengths, such that he didn't fear normal fire arms. To be able to figure out his secret, a lot of underworld organizations as well as countries put a high bounty on his head.

Initially, a lot of top ranked assassins and mercenary groups took on this task to capture 'Ghost Blade' but none succeeded. That was not to say they didn't find him but rather none of them ever returned alive while the Ghost Blade's reputation rose to a completely new level. Everyone now believed that this man was no longer human because he was documented to have fought against a whole squadron of elite soldiers armed to the teeth with the most advanced weapons but none of them lived to tell the tale while he walked out of it without a scratch.

Ever since then, no one was willing to take up the suicide mission. Even after the reward was increased numerous times, still no one was willing to step up. No matter how wonderful money may be, what was the point if you are dead? Only the living can get to enjoy money after all. The name "Ghost Blade" on the other hand became a taboo amongst the underworld's bounty list.

Even with such a reputation, many clients would still rush to line up for his services. The reason being that he possessed superior marksmanship, eyesight, immeasurable martial arts prowess as well as monstrous speed. His cultivation in both fistfights and blade fights are exceptional. However, the biggest reason remains that his rate of success is one hundred per cent! This achievement was truly unprecedented!

Despite his cold blooded nature, he was still a very trusting person. He trusted his four companions whom he had been together with since childhood. Only these four knew of his humble background and sad past. And also it was these same companions that led to his downfall.

They leaked news of Rayden's only weakness which was his younger sister to his enemies. An accident during their childhood led to his younger sister being kidnapped by a very notorious slave trader and he had been desperately searching for news of that slave trader ever since.

Desperate to get hold of the secret to Rayden's inhuman strength, his enemies set up an ambush and leaked news of the slave trader that he had been searching for. This man was coincidentally also responsible for the death of his parents.

Even though he finally found out that this was an ambush that was orchestrated by the collaboration between his trusted companions and his enemies, he was still determined to capture this man. And the result proved that these people still had underestimated his strength. Rayden singlehandedly massacred over thirty top rated Special Forces agents and bounty hunters on his way towards the location where the slave trader was kept. When he finally got his hands on the slave trader, the remaining ambusher's courage had been shattered to pieces. From the combat prowess that Rayden had displayed, these people knew that if he wished to, he could easily escape out of there.

After witnessing Rayden's new display of astonishing combat prowess, the greed in his enemies' heart grew even stronger. They wanted to get their hands on Rayden's secret no matter what. They had investigated Rayden's background and knew he was an ordinary person so they were desperate to find out the secret of his miraculous strength.

They instantly doubled the already astronomical bounty on Rayden's head and announced it to the ambushers who were battling Rayden!


	3. Chapter 3 - Rayden D Chronus (Part 3)

**Chapter 3: Rayden D. Chronus (Part 3)**

When the people ambushing him saw the new bounty being offered, they were now invigorated by the prospect of getting their hands on such a huge bounty so they disregarded the previous strength that Rayden had displayed and once again launched attacks towards him.

Having accomplished his long standing wish, he subconsciously touched the necklace on his neck with his bloody hands. This necklace was the only keepsake left behind by his parents after they disappeared and also the secret to his strength.

The moment his bloody hands touched this crystal, it shone brightly and crazily begun to absorb his blood. After absorbing his blood, it began to emit a blinding golden light which instantly enveloped him. His last memories were that of the twenty firearms shooting at him.

He was still holding unto this necklace and thinking of his only remaining relative in this world; his sister, when he lost consciousness. Even though he had finally found out her location, he would never have the chance to meet her again.

He woke up two years ago in this One Piece world in the body of this boy who coincidentally shared the same first name as him. Initially this boy had a very weak physique with his attributes averaging at 0.5. One must know that the average attribute of an adult in this world is 1.0 two being the stronger. People with attributes greater than two can no longer be considered average people.

Fortunately, the necklace which had been the cause of his rebirth also travelled with him and finally fused with him after he had successfully been reborn. He got two gifts after the necklace fused with him. The first was the Lightening core which had fused with his heart and the system. But the lightening core had been locked because his body was too weak to awaken it.

What frustrated him the most was that the system did not come with any kind of guide or manual o he had to experiment and discover everything on his own. It took him also three months to figure out almost all the functions of this system.

According to the grading of the system, this world, every normal human being possesses some basic body attributes at birth. These have been categorized into five different attributes: Strength, Agility, Vitality, Intelligence and Awareness. One's strength was differentiated based on these four basic attributes.

Strength was primarily used to quantify a person's musculature and body strength. This attribute was very important for close combat fighters. The strength attribute would affect one's base damage when using close combat weapons, and it also affected one's melee accuracy. After continues experimentation, he found out that this strength attribute affected his actual muscle density as well as defense.

For an ordinary man, having 1.0 to 1.5 Strength was quite normal. An adult with 2.0 strength would be considered to be fairly strong.

Agility was used to quantify body synchronization, flexibility, reflexes, and balance. It was extremely vital for every kind of fighter in this world.

Vitality represented a person's health and endurance. Any increase in physique would improve a person's Fortitude and Concentration. Therefore, it is very important for all everyone. A person's Vitality also determines his recovery rate. The minimum Vitality for any human is 0.2. If a human's vitality dropped below that, they would die.

Intelligence determined a person's learning and inferring ability. This attribute was especially important for people of this world as it would determine how fast they would comprehend skills and battle techniques. People with stronger souls usually progress very fast in learning battle skills and unearthing abilities of Devil Fruits.

Awareness determines a person's willpower, Judgment in various situations, Perception to the surroundings and Intuition. From this, Rayden figured out that if his Awareness attribute was very high, he also had a very big chance of awakening Observation Haki very early.

Apart from these, he also found another interesting attribute which was the Battle Energy. Every time he engages in a life and death battle, if he kills his opponent, he will get an amount of battle energy. Even if he doesn't kill his opponent, as long as he wins, he would get 1/3 of the supposed battle energy. He doesn't get any battle energy when he fights against beasts.

This battle energy can be used to increase both his battle attributes and battle skill proficiency. In terms of attributes, the rate of increase is 10:0.1, meaning ten battle points are needed to increase his basic attribute by 0.1. In terms of battle skills, because the level of every skill is different and also the difficulty in practicing it is different, the battle energy needed for the increase of each skill's proficiency is different. Some require only 5 battle energy points to increase whilst others require as much as 20.

With the help of this system and his unceasing limit body training, he was finally on the brink of unlocking the Thunder Core. This was a treasure was the secret to his strength in his previous world. Even though this thunder core had not fused with him then it released a golden substance which strengthened his body constantly and increased the effects of his training. Now that it had fused with him, he was looking forward to the benefits it would bring him.

This One Piece world is a very dangerous world. As a One Piece fan in his previous life when he was younger, he knew how dangerous this world was for ordinary people. Compared to his previous world of rule and order, this world is too dangerous. For those who can destroy cities with a single punch, ordinary people like him are like ants. As long as you have enough strength, rules simply don't exist for you in this world.

With a single wave on the hand of such strong people, just the aftershock is enough to send him to his maker. As a person who stood at the peak of his previous world, of course he didn't want to be a weakling and with his hard work as well as the help of this system, he knew he could also stand at the peak of this world in the future.


	4. Chapter 4 - Invitation

From the impact created when he clashed with Bloody Axe Rand, he could basically determine that Rand's comprehensive combat assessment could be placed at the peak of F level. So he wasn't much weaker than him. What made the difference was his much more abundant combat experience as well as overbearing blade skill which dispatched him before he had time to react.

After checking the amount of battle energy points that he had, Rayden put away the attribute panel with a thought a moved towards the dead body of Bloody Axe Rand.

In addition of Bloody Axe Rand, the number of pirates that Rayden had hunted since he began his bounty hunting career six months ago is six. He had hunted three pirates who had bounties of ฿ 1,000,000, ฿ 1,500,000 and ฿ 2,400,000 respectively and all these pirates had a combat assessment of F-. After that he moved to F ranked pirates who had bounties of ฿ 2,800,000 and ฿ 3,500,000 respectively. Bloody Axe Rand was the last pirate in this rank that he could hunt. The reason why he hunted three people from each rank is that he could only get battle energy points from three people in each rank. So for now, if he battled and killed another F ranked combatant, he wouldn't get any battle point.

A bounty reflects both the threat and power of an individual. Engaging in activities deemed criminal by the World Government or associating with groups which engage in them is enough to warrant significant bounties even if the criminal is not powerful themselves. In particular, direct opposition to the World Government, no matter the reason, is treated as a serious offense, and bounties are issued accordingly.

In the One Piece world, a pirate's bounty is high or low depending on the threat of a person's observed combat abilities, inspiring criminal acts when provoked or inciting others to act 'criminally' (for example, Whitebeard destroying Marine ships that followed his fleet for reconnaissance and Dragon leading his organisation to conquer nations affiliated with the World Government) and also having knowledge deemed illegal by the World Government, as with Nico Robin.

Since Rayden, can't determine an opponent's combat level before he actually sees them fight or clashes with them, he uses their bounties to determine their combat power and hunts them accordingly. That is why he took on the occupation of a bounty hunter.

After clearing the rubble, he picked up the dead body of Rand and made his way to Shells Town where a navy branch was located to claim the bounty of 'Bloody Axe's' head.

…

A few hours later, he finally arrived at Shells town with the body of his 'Bloody Axe' Rand over his left shoulder.

As he entered the town, because of his recent exploits of hunting pirates in and around this Island, some of the residents recognised him.

"Is that 'Twin Blade' Rayden? Who's that on his shoulder?" with a frown on his face, one of the residents of Shells Town who recognized Rayden asked but no one answered him.

A lot of the ordinary citizens that recognised Rayden as the bounty hunter who had been very active recently stayed away from him. In the one piece world, successful bounty hunters will often inevitably become well-known, especially by wanted criminals, and even normal civilians may become afraid of them. Since they operate outside the law, bounty hunters have been known to partake in criminal activity, although being labelled as criminals typically prevents them from bounty hunting again since they can no longer deal with the government.

This was the reason why most of the citizens shunned him when they recognised him as a bounty hunter. But Rayden didn't care about this. First of all, joining the Navy was out of the question for him. For someone who had stayed outside the law for so long in his previous world, how could he become a 'watch dog' for the World Government and those 'good for nothing' World Nobles. Also, for now, since he was not strong enough, he didn't want to become a pirate and get the Navy on his tail.

"'Twin Swords' Rayden? How could he come here again? Wasn't it just last month that he delivered the head of Zack 'The Butcher'?"

Some of the residents who recognized the person on Rayden's shoulder became very surprised. It was quite surprising for a bounty hunter to be this active since they usually hunt when they are in need of money.

Rayden ignored the commotion being caused by the residents of this town and gradually walked towards Navy branch.

But he was surprised when he got to the Navy branch and noticed the Highest Ranked Marine Officer of this branch, Marine Captain Kuzumi standing outside the main gates wearing his usual large, billowing coat like a cape, with some marines standing by him. Standing by his right hand was a very tall and muscular, and quite intimidating man with blonde hair holding an axe in his left hand which was currently resting on his left shoulder. When Rayden saw this young man for the first time, he thought his face looked familiar but after thinking about it for some time he still wasn't able to recognize him.

It wasn't until he later heard his name that he remembered him. This man was Morgan; the future father of Helmeppo! Currently, he was still a Lieutenant Commander. In addition to these two, there were other Marines standing there waiting for him. It seemed that they had received news of his arrival and came out to meet him.

"Ha Ha, Captain Kuzumi, you brought out such an entourage to greet me? You shouldn't have….!"

Hearing Rayden, Captain Kazumi's already bad mood got even worse but he pretended not to have heard Rayden's mocking comment and looked at the dead body on Rayden's shoulder and asked with a placid expression, "Who is it this time?"

The only reason why he had gathered here with these marines was because the higher ups had noticed the potential of this young bounty hunter and had instructed him to try and invite him into the Navy.

With Gol D. Roger beginning the Golden Age of Piracy seven years ago, more talented people needed to be drafted into the Navy to manage the chaos that was now spreading everywhere!

Also, the fact that it wasn't the Navy capturing all these pirates around his base, but rather bounty hunters like Rayden was a slap in his face. That was why he wasn't very happy whenever he saw Rayden here.

Hearing Captain Kuzumi's manner of speech, Rayden knew that this man had become angry so he stopped making fun of him. He immediately dropped the corpse on his shoulder!

'Bang!'

Dust scattered everywhere when the corpse landed on the floor, "Its 'Bloody Axe' Rand, with a bounty of ฿ 4,000,000!" while saying this, Rayden proceeded to take a bounty poster from his pocket and presented it to them. He wanted Captain Kuzumi to compare the image on the poster with the face of the corpse.

"What!" some marines exclaimed in surprise when they heard Rayden. In this base, no one was the 'Bloody Axe' Rand's match except for their Captain and even he was not confident in being able to kill him. So they were shocked when they heard that Rayden had been able to kill Rand.

"No wonder the headquarters is also interested in him. This boy really has potential." This thought also flashed through Captain Kuzumi's head when he heard Rayden. He proceeded to take the bounty poster from Rayden's hand and personally verified the dead body's identity.

After confirming 'Bloody Axe' Rand's identity, Captain Kuzumi signed and stood up looking carefully at Rayden.

"His identity has been confirmed. It's really 'Bloody Axe' Rand! Rayden, you'll have to wait a while for us to confirm with Headquarters before you receive the reward" Captain Kuzumi's attitude had now drastically changed when he confirmed the identity of Rayden's latest kill. From this, he could tell that Rayden was at least on the same level or perhaps even stronger than him. When the Headquarters had told him to try to invite Rayden, they knew also told him about his age; 15 years! A young man at this age with such strength would have a great future if he joined the Navy.

"Don't worry, I'm not in a hurry. Take as much time as you need!" With a smile on his face, Rayden said this and suddenly sat cross legged on the floor in front of the marine base. Because of the strength that was now evident fom his recent kill, now, nobody minded Rayden's attitude.

Kuzumi motioned Lieutenant Commander Morgan to go inside and make the report while he waited with Rayden. Morgan then immediately run into the base. Whilst waiting for Lieutenant Commander Morgan o return, Captain Kuzumi looked closely at Rayden and said, "Speaking of which, the Navy has recently been recruiting talented new people. My Superiors at the Navy Headquarters asked me if you would like to join the Navy. If you wish to join, you can immediately gain the rank of Marine Commander!"

"Me, join the Navy?" Rayden was very surprised when he heard this.


End file.
